2 INTRODUCTION

This is the Environmental Protection Agency’s (E PA or the Agency) Final Work Plan (FWP) for the registration review of imazethapyr. This wo rk plan addresses public comments received concerning the Preliminary Work Plan (PWP), which was posted in the imazethapyr registration review docket (EPA-HQ-OPP-2013-0774). This case includes the active ingredients imazethapyr and imazethapyr ammonium salt. Imazethapyr and imazethapyr ammonium salt are systemic herbicides of the imidazolinone herbicide family. They are regi stered for use as selective herbicides to control grasses a nd broadleaf weeds in certain agri cultural use sites and are also registered for use in certain non-agricultural use sites. Throughout this FWP, EPA will refer to the two active ingredients in th e case collectively as imazethapyr.

The Agency is implementing the registration revi ew program pursuant to Section 3(g) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each registered pesticide every 15 years to determine whether it continues to meet th e FIFRA standard for registration. Changes in science, public policy, and pesticide use practices occur over time. The registration review program is intended to make su re that, as the ability to assess risk evolves and as policies and practices change, al l registered pesticides continue to meet the statutory standard. The public phase of registration review begins wh en the initial docket is opened for each case. Information on this program is provided on the Agency’s website. 1

The FWP begins with any updates since the PWP wa s issued. Next is a summary of substantive comments received during the public comment peri od for the PWP concerning anticipated data needs, expected risk assessments, or the estimated timeline identified in the PWP, and a summary of the Agency’s responses to those comme nts. This section is followed by registration review planned data needs, risk assessments expected to be conducted, and the projected registration review timeline for imazethapyr. Las tly, there is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

There are no additional update s on imazethapyr since the PWP.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

During the 60-day public comment period on th e imazethapyr Preliminary Work Plan, which opened on March 28, 2014 and closed on May 2 7, 2014, the Agency received public comments pertaining to the imazethapyr case from four stakeholders. Comments were submitted by BASF Corporation (BASF), the California Department of Pesticide Regulation (CDPR), the FIFRA Endangered Species Task Force (FESTF), and th e National Alfalfa & Forage Alliance (NAFA). The comments do not address the timeline or the pl anned risk assessments described in the PWP, but they do address the planned ecological data requirements. In the PWP, EPA also solicited comments on the specific topics of environmenta l justice, water quality concerns, and trade irritants; EPA received groundwater monitoring data from CDPR, but no other comments or information were received on those issues.

1 http://www.epa.gov/oppsrrd1/registration_review/3 This section does not capture every comment made about the PWP nor all of the Agency’s responses. Summarized below are public comments that resulted in change s to the anticipated registration review data needs or are of a broader regulatory nature. Public comments and EPA responses in their entirety are located in the docket EPA-HQ-OPP-2013-0774. Summarized public comments and Agency responses related to the anticipated ecological risk assessment or data needs are in the Response to Public Comments on the Imazethapyr and Imazethapyr Ammonium Salt Registration Review Problem Formulation . In response to comments regarding use and usage information, EPA has updated the BEAD Chemical Profile (BCP) for Registration Review Imazethapyr Chemical Case [Inc ludes Imazethapyr (128922) and Imazethapyr, Ammonium Salt (128923)]

. Comments submitted by NAF A in EPA-HQ-OPP-2013-0774-0012.

1. Comment: NAFA submitted comments expressing support for the continued registration of imazethapyr for use in alfalfa seed and hay pr oduction and provided information about the uses and benefits of imazethapyr. Th ey discussed the importance of a lfalfa seed and hay as rotational crops, discussed the high degree of weed cont rol that alfalfa hay/seed crops require, and the importance of weed-free alfalfa hay/seed for expo rt. They also discussed the way alfalfa for hay is planted which makes cultivation unsuitable for control of weeds, listed some problems with herbicides that are alternatives to imazethapy r, discussed some reas ons glyphosate resistant alfalfa and glyphosate use are not replacements for imazethapyr, and discussed the importance of the residual weed control offered by imaz ethapyr. They also commented on the importance of rotating and tank mixing herbic ides with different modes of action as an important tool for managing herbicide resistant weed s in all crops, and the import ance to alfalfa growers of imazethapyr’s mode of action (ALS inhibitor).

Response: EPA thanks NAFA for their commen ts, and will consider the information during registration review.

Comments submitted by BA SF in EPA-HQ-OPP-2013-0774-0015.

2. Comment: BASF submitted comments pertaining to the anticipated data needs listed in the imazethapyr PWP and the EFED Problem Formulation.

Response: Agency responses related to each comment from BASF regarding anticipated data needs are located in the Response to Public Comments on the Imazethapyr and Imazethapyr Ammonium Salt Registration Re view Problem Formulation. The comments from BASF resulted in two changes pertaining to the anti cipated data needs listed in the PWP: 1) the previously anticipated requirement for a study of honey bee toxicity from residues on foliage (guideline number 850.3030) has been removed fro m the list of planned data needs in the FWP and 2) EPA is correcting th e test material for the non-guid eline honeybee la rval toxicity study; this study should be conducted with the technical grade active ingredient (TGAI), rather than a typical end-use product (TEP ) as previously listed in the PWP.

3. Comment: BASF submitted a comment on use and usage information, stating that they “would like to correct the reference to corn and rice as genetically modified. Both corn and4 rice, as listed on imazethapyr- based products, are herbicide tolerant but non-genetically modified crops (non-GM).”

Response: EPA has updated the BEAD Chemical Profile (BCP) for the imazethapyr case to remove references to corn and rice as gene tically modified. The upda ted BCP will be posted in the imazethapyr registration review docket.

PLANNED DATA NEEDS

Table 1 below summarizes the planned data needs for imazethapyr based on the Registration Review Problem Formulation for Imaz ethapyr and Imazethapyr Ammonium Salt and Imazethapyr Human Health Assessment Scoping Document in Support of Registration Review, as well as the Response to Public Comments on the Imazethapyr and Imazethapyr Ammonium Salt Registration Review Problem Formulation . The table has been updated since the PWP to reflect public comments which resulted in changes to the data needs. The previously anticipated requirement for a study of honey bee toxicity of residues on foliage (guideline number 850.3030) has been removed from the list of planned data needs in Table 1 below. Table 1 below also clarifies that both an acute and a chronic larval toxicity studies ar e needed and corrects the test material for both; these studies should be conduc ted with TGAI, rather than TEP as previously listed in the PWP. In addition, the standard ti meframe for the honey bee larval chronic oral toxicity has been listed as twenty-four months.

Table 1: Planned Data Needs for the Imazethapyr Registration Review Case

Guideline Number 2 Study Title Test Material Estimated Timeframe (Months from receipt of DCI)

Anticipated Data Needs for the Parent

850.3020 Honey bee acute contact toxicity Imazethapyr TEP or imazethapyr ammonium salt TEP 12

Nonguideline 3 Honey bee acute oral toxicity Imazethapyr TEP or imazethapyr ammonium salt TEP 12

2 On June 27, 2012, EPA announced certain revisions in harmonized guideline series 850 – Ecological Effects Tests

– including renumbering and other designations or changes for some guideline studies. See “Final Test Guidelines; OCSPP 850 Series; Notice of Av ailability” 77 FR 38282 , June 27, 2012. http://www.regulations.gov/#!documen tDetail;D=EPA-HQ-OPPT-2009-0154-0028

3 Although an OCSPP test guideline is not available, OECD 213 may be used.5 Table 1: Planned Data Needs for the Imazethapyr Registration Review Case

Guideline Number 2 Study Title Test Material Estimated Timeframe (Months from receipt of DCI)

Nonguideline 4 Honey bee larval acute oral toxicity Imazethapyr TGAI or imazethapyr ammonium salt TGAI 12

Nonguideline 5,6 Honey bee larval chronic oral toxicity Imazethapyr TGAI or imazethapyr ammonium salt TGAI 24

850.4100 Terrestrial plant toxicity, seedling emergence Imazethapyr TEP and imazethapyr ammonium salt TEP 12

850.4150 Terrestrial plant toxicity, vegetative vigor Imazethapyr TEP and imazethapyr ammonium salt TEP 12

Anticipated Data Needs for the CL266858 Degradate

850.4400 Aquatic plant growth (aquatic vascular plant toxicity) Degradate CL266858 12

RISK ASSESSMENTS FOR REGISTRATION REVIEW

During registration review, the Agency will conduct a comprehensive ecological risk assessment, including an endangered species assessment, for all uses of imazethapyr. For human health, EPA has determined that a qualitative assessment is sufficient based on the low toxicity of imazethapyr; therefore, EPA will not conduct revised quantitativ e dietary, residential, and occupational risk assessment s during registration review.

Table 2 below summarizes the planned registrati on review risk assessments based on the EFED Problem Formulation and HED Scoping Documen t; the planned assessments have not changed from what was included in the PWP.

4 Although an OCSPP test guideline is not available, OECD 237 may be used. 5 The November 2013 draft OECD protocol for a honey bee brood test using repeated doses may be used for this study. Please see http://www.oecd.org/env/ehs/testing/Draft_GD_h oneybees_rep_exp_for_2nd_CR_25_November_2013.pdf for details.

6 A protocol should be submitted to the Agency for review and approval prior to study initiation.6 Table 2: Planned Risk Asse ssments for the Imazethapyr Registration Review

Type of Risk Assessment Conduct? Notes Ecological and Environmental Fate Comprehensive ecological (species to be assessed include terrestrial and aquatic organisms), including endangered species Yes EPA anticipates conducting an updated comprehensive ecological risk assessment during registration review. The new assessment will incorporate the most up-to-date modeling methodologies, updated toxico logical endpoints, and data submitted under the anticipated registration review data call-in. Incidents Will check for updates For a discussion of reported ecological incidents, see page 19 of the Problem Formulation. Human Health Dietary Food No The most recent dietary exposure assessment was conducted for the 2005 human health risk assessment. No dietary risks of concer n were identified. Since it has been determined that a qualitative assessment is sufficient based on the low toxicity of imazethapyr, a quantitative dietary exposu re assessment is not needed for registration review. Drinking water No

Occupational Handlers (mixers, loaders, applicators) No The most recent occupational and residential exposure assessment was conducted for the November 2005 human health risk assessment. No occupational risks of concern were identified. Since it has been determined that a qualitative assessment is sufficient based on the low toxicity of imazethapyr, quantitative occupational exposure assessments are not needed for registration review. Post-application No

Residential Handlers No The most recent occupational and residential exposure assessment was conducted for the November 2005 human health risk assessment. No risks of concern were identified. Residential exposure scenarios have not been assessed; however, since it has been determined that a qualitative assessment is sufficient based on the low toxicity of imazethapyr, quantitative occupational and residential exposure assessments are not needed for registration review. Post-application No

Other7 Aggregate No Evaluates the comb ined risk from dietary and residential exposures. The most recent aggregate exposure assessment was conducted for the November 2005 human health risk assessment. No risks of concern were id entified. Since it has been determined that a qualitative assessment is sufficient based on the low toxicity of imazethapyr, quantitative aggregate assessments are not needed for registration review. Cumulative No Not applicable. Imazethapyr and imazethapyr ammonium salt have not b een identified as members of a cumulative group that shares a common mechanism of toxicity. Tolerances Yes Tolerances for im azethapyr are established in 40 CFR §180.447. These include a tolerance for imazethapyr on imported canola. During registration review, EPA plans to update the tolerance expression for harmonization purposes and to conform to current EPA policy. Incidents Will check for updates For a discussion of reported human incidents, see pages 7-8 of the Scoping Document and the Imazethapyr: Tier 1 Revi ew of Human Incidents

.

TIMELINE

EPA has created the following estimated time line for the completion of the imazethapyr registration review in Table 3 be low. The projected timeline has been updated since the PWP to reflect the standard time that may be necessa ry to conduct the honey bee larval chronic oral toxicity study, which is twenty-four months.

Table 3: Registration Review for Imazethapyr – Projected Registration Review Timeline

Activities Estimated Date Opening the Docket Open Docket and 60-day Public Comment Period Mar. 2014 – Completed Close Public Comment May 2014 – Completed Case Development Final Work Plan Sept. 2014 – Completed Issue DCI 2014 Oct. – Dec. Data Submission 2016 Oct. – Dec. 60-day Public Comment Period for Draft Risk Assessments 2018 April - June Registration Review Decision 60-day Public Comment Period fo r Proposed Registration Review Decision 2019 Jan. - March

Registration Review Decision and Begin Post-Decision Follow-up 2020 Total (years) 68 NEXT STEPS

As noted previously, the Agency plans to re quire several ecological effects studies for imazethapyr through a Data Call-In Notice, expected to be issued in late 2014.